Selecting Good Passwords

Rationale

The object when choosing a password is to make it as difficult as possible for a cracker to make educated guesses about what you've chosen. This leaves him no alternative but a brute-force search, trying every possible combination of letters, numbers, and punctuation. A search of this sort, even conducted on a machine that could try one million passwords per second (most machines can try less than one hundred per second), would require, on the average, over one hundred years to complete.

What Not to Use

Don't use your login name in any form (as-is,
reversed, capitalized, doubled, etc.).

Don't use your first or last name in any form.

Don't use use your spouse's or child's name.

Don't use other information easily obtained about
you (like Bujinkan or Ninja words). This includes license plate numbers, telephone
numbers, social security numbers, the brand of your
automobile, the name of the street you live on, etc.

Don't use a password of all digits, or all the same
letter. This significantly decreases the search time
for a cracker.

Don't use a word contained in (English or foreign language)
dictionaries, spelling lists, or other lists of words.

Don't use a password shorter than six characters.

What to Use

Do use a password with mixed-case alphabetic characters.

Do use a password with nonalphabetic characters,
e.g., digits or punctuation.

Do use a password that is easy to remember, so you
don't have to write it down.

Do use a password that you can type quickly, without
having to look at the keyboard. This makes it harder
for someone to steal your password by watching over
your shoulder.

Method to Choose Secure and Easy to Remember Passwords

Choose a line or two from a song or poem, and use the
first letter of each word. For example, ``In Xanadu
did Kubla Kahn a stately pleasure dome decree''
becomes ``IXdKKaspdd.''

Alternate between one consonant and one or two
vowels, up to eight characters. This provides nonsense
words that are usually pronounceable, and thus
easily remembered. Examples include ``routboo,''
``quadpop,'' and so on.

Choose two short words and concatenate them together
with a punctuation character between them. For example: ``dog;rain,'' ``book+mug,'' ``kid?goat.''